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<title>STABS: Register Variables</title>

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<a name="Register-Variables"></a>
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Next: <a href="Common-Blocks.html#Common-Blocks" accesskey="n" rel="next">Common Blocks</a>, Previous: <a href="Global-Variables.html#Global-Variables" accesskey="p" rel="prev">Global Variables</a>, Up: <a href="Variables.html#Variables" accesskey="u" rel="up">Variables</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Register-Variables-1"></a>
<h3 class="section">4.3 Register Variables</h3>

<a name="index-N_005fRSYM"></a>
<a name="index-C_005fRSYM"></a>
<p>Register variables have their own stab type, <code>N_RSYM</code>
(<code>C_RSYM</code> for XCOFF), and their own symbol descriptor, &lsquo;<samp>r</samp>&rsquo;.
The stab&rsquo;s value is the number of the register where the variable data
will be stored.
</p>
<p>AIX defines a separate symbol descriptor &lsquo;<samp>d</samp>&rsquo; for floating point
registers.  This seems unnecessary; why not just just give floating
point registers different register numbers?  I have not verified whether
the compiler actually uses &lsquo;<samp>d</samp>&rsquo;.
</p>
<p>If the register is explicitly allocated to a global variable, but not
initialized, as in:
</p>
<div class="example">
<pre class="example">register int g_bar asm (&quot;%g5&quot;);
</pre></div>

<p>then the stab may be emitted at the end of the object file, with
the other bss symbols.
</p>



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